1. Field of the Invention
The present invention relates to an improved driving mechanism for a syringe-pump driving apparatus for controlling the discharge and drawing-up of a plurality of syringe pumps.
2. Description of the Related Art
Syringe pumps are widely used in a variety of tests and measurements for controlling the amount of liquid discharged and drawn-up with high precision. The amount of liquid discharged and drawn-up is determined by the amount of movement of a plunger, and drive screws are generally used as the driving mechanism therefor.
Driving apparatuses that discharge and draw up liquid in multiple flow paths, by connecting a plurality of syringe pumps in parallel and driving them simultaneously, are also used. One example of such an apparatus is described in U.S. Pat. No. 5,988,236. The syringe-pump driving apparatus described in U.S. Pat. No. 5,988,236 adopts a structure in which a holder that fixes a plurality of syringes is driven by means of a single drive screw, and the holder is kept in balance by means of a plurality of guide rails while moving. However, since the apparatus described in U.S. Pat. No. 5,988,236 has only a single driving point, when the resistance of each syringe is changed due to deterioration, thus degrading the dynamic balance of the holder, it is difficult to move the holder while keeping it straight. As a result, there is a drawback in that the precision of the syringes when discharging and drawing-up liquid is reduced.